Recently, portable electronic devices and electronic devices for displays tend to be light, thin, short, and compact, speedily, signal transfer speeds between components in the electronic devices become high, and circuit boards are in progress with high-integration microcircuits, to thereby have a tendency of increasing damage of EMI (Electromagnetic Interference) of signals due to electromagnetic noise generated between the adjacent circuits.
In addition, if electromagnetic waves generated from electronic devices are exposed to the human body for a long time, the human body may suffer from disorder such as glaucoma, and lowering of fertility.
Accordingly, in order to block electromagnetic waves, the portable electronic devices and electronic devices for displays, mainly use a type of shielding electromagnetic waves by attaching electromagnetic wave shielding sheets onto the inner surface of a case, circuit components that directly generate electromagnetic waves, or the surface of a built-in antenna.
As disclosed in Korean Patent Application Publication No. 10-2009-0078620, on Jul. 20, 2009, a conventional electromagnetic wave shielding sheet includes: a substrate sheet formed of a synthetic resin film; and a metal deposition layer that is sputtered on the surface of the substrate sheet, wherein the metal deposition layer is made of at least one selected from the group consisting of copper (Cu), nickel (Ni), zinc (Zn), aluminum (Al) and manganese (Mn).
However, the conventional electromagnetic wave shielding sheet becomes thick since the substrate sheet is formed of a synthetic resin film, and thus the overall thickness of a portable electronic device using the conventional electromagnetic wave shielding sheet is increased.
Further, when depositing a conductive metal on the surface of the synthetic resin film, the conductive metal layer may cause peeling to thereby cause a problem of degrading electromagnetic wave shielding performance.